Dispenser for xerographic developer toner



0a. 6, 1970 w. KNECHTEL 3,532,256

DISPENSER FOR XEROGRAPHIC DEVELOPER TONER Filed Oct. 21. 1968 2 Sheets-Sheet 1 NVENTOR.

fwilhelm 9(ncchr 1 MW? ATTORNW V DISPENSER FOR XEROGRAPHIC DEVELOPER TONER Filed Oct- 21. 1968 W. KNECHTEL Oct. 6, 1970 2 Sheets-Sheet 2 United States Patent 3,532,256 DISPENSER FOR XEROGRAPHIC DEVELOPER TONER Wilhelm Knechtel, Rodheim-Bieber, Germany, assignor to The Singer Company, a corporation of New Jersey Filed Oct. 21, 1968, Ser. No. 769,152 Claims priority, application Germany, Nov. 24, 1967, 1,597,833 Int. Cl. G01f 11/00 US. Cl. 222-227 6 Claims ABSTRACT OF THE DISCLOSURE Apparatus for automatically controlling the dispensing of toner for mixture with iron dust in the developer powder container of an electrostatic processing system. During each revolution of the device, a series of rotating agitator blades are effective to prevent agglomeration of the toner. While the toner is being mixed, a pusher plate moves toner into a screened counterbored orifice which forms a sieve. As the agitator blades are revolving and at a predetermined time in each revolution, a cam controlled plunger drops into the orifice forcing toner through the screen and into a reservoir for mixture with a carrier material.

BACKGROUND OF THE INVENTION This invention relates to toner dispensing devices and more particularly to an automatic control of such devices to maintain the image density constant during electrostatic printing operations.

In the art of electrostatic printing, an electrostatic latent image is subjected to a development process whereby a developer powder consisting of a mixture of toner and a carrier such as iron dust, for example, are applied by any one of various methods to the latent image area. The toner adheres to the charged image area while most of the carrier or iron dust returns to the developer container. Generally, the replenishment of the toner to the developer powder is manually controlled and is at the discretion of an operator. Unless the proper ratio of toner-to-carrier is maintained, the image density will not be of a consistently good quality.

The toner, because of its very nature, has a tendency to agglomerate, that is, forms small lumps much like a meal flour and cannot be applied in a finely atomized form to the electrostatically charged image area. Once it is mixed with the carrier or iron dust it is capable of flowing and, in some instances, the toner and iron dust are pre-mixed to the correct ratio and thereafter introduced into the developer container. In the use of the pre-mixed method and due to the continuous consumption of toner, the carrier powder remaining must be removed often from the developer container and then replaced by a fresh mixture to assure the correct mixture ratio of iron dust and toner.

SUMMARY OF THE INVENTION The apparatus of the present invention is for the purpose of automatically dispensing a controllable amount of toner for an electrostatic developer mixture of toner and carrier. During each operation of the toner dispenser, agglomeration or lumping of the toner is prevented by agitation as toner is moved into position relative to a screened outlet of a predetermined size, whereupon a plunger moves downwardly to force a given amount of toner through the screen or sieve into the developer container. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:

FIG. 1 is a sectional elevational view of the refilling device,

ice

FIG. 2 is a sectional plan view taken on the plane indicated by line 22 in FIG. 1,

FIG. 3 is a detail of an agitator blade,

FIG. 4 is a view of the cam plate, and

FIG. 5 is a sectional plan view showing the screened orifice and the pusher plate, the view being taken on the plane indicated by line 55 in FIG. 1.

Referring to FIG. 1, a container or dispenser 1 is filled with toner. In the bottom plate of the container 1 is a circular opening 2 which is counterboard to receive a screening 3 secured therein and serving as a sieve. Upon disposal of toner in the area of the screen opening 2, a plunger 4 having a circular head 6, disposed at its lower offset end, moves downwardly so that the head 6 forces toner through the screen 3. The powdered toner then falls into the developer container or reservoir 8 for mixture with a carrier such as iron dust. This mixture of developer material is taken from the container and applied in a well-known manner, such as by means of a brush, to the latent image area of a charge photoconductive surface, the brush rotating within the reservoir of developer material.

A shaft 7 of the plunger 4 is supported for reciprocatory movement in suitable apertures in respective guide flanges 10 and 11 of a channel bracket 23 secured by means of a pair of screws 24 (FIG. 2) to the wall of the container 1. At its upper end, shaft 7 is provided with screw threads and a diametrically disposed slot 25 within which slot an arm or rod 13 is adjustably secured by means of nuts 12 threaded on shaft 7. At its one end, arm 13 projects through a suitable vertical slot 26 in the wall of container 1 and outwardly of the wall to support one end of a spring 9, the other end of which is supported on a pin 27 secured on the container wall. At its other end, arm 13 is formed in a loop engaging a shaft 16 for sliding movement axially of the shaft. Shaft 16 is rotatably supported in the bottom plate of and is concentric with container 1 and is driven through suitable gearing 28 by a motor 17, which is energized with each operation of the machine.

Spring 9 normally serves to urge arm 13 and lunger 4 downwardly to maintain arm 13 in engagement with a cam plate 15 at a point on the arm intermediate shafts 7 and 16. Cam plate 15 is substantially cup-shaped and is secured on the upper end of a hub or sleeve 29 which, in turn, is secured on shaft 16 by means of a set-screw 30. Normally, the plunger 4 is in the position shown in FIGS. 1 and 2 the arm 13 resting on the high point of cam plate 15. However, immediately upon counter-clockwise rotation of the cam plate 15, as seen in FIG. 2, the spring 9 abruptly pulls the arm 13 downwardly into engagement with the low point of the cam and the head 6 of the plunger 4 forces toner, deposited at the opening 2, through the screen 3. The limit of the downward movement of the plunger 4 is determined by the engagement of the lower nut 12 with the guide flange 10. The diameter and mesh of the screen 3 and the angular velocity of the cam plate 15 controlling an intermittent operation of plunger 4 determine the amount of toner supplied to the reservoir 8 to ensure the proper ratio of toner to carrier with each operation of the machine.

In order to ensure a sufficient deposit of toner at the opening 2, the lower end of the plunger shaft 7 is offset as at 18 and the opening 2 is disposed inwardly away from the wall of container 1. To further ensure the depositing of toner at the opening 2, a plate or disk 19 (FIGS. 1 and 5) is secured on the lower end of the sleeve 29 for rotation with shaft 16 and cam plate 15. An accurate opening 31 approximating is provided in plate 19 so that as the plate is rotated counter-clockwise in FIG. 5, the leading edge 32 serves to move toner into the area of opening 2. Upon completion of each revolution of plate 19 the trailing edge 33 of the plate is clear of the opening 2 so that immediately beginning a succeeding revolution, the plunger 4 can perform its function. Thereafter, the cam plate restores the plunger 4 to its inactive position, the rise of the cam being such that immediately prior to 180 rotation of the plate 19, the head 6 of the plunger 4 will be raised to a position out of the path of the leading edge 32 of the plate 19.

In order to prevent the formation of lumps of toner in container 1 above plate 19, two series of radially disposed fingers or blades and 21 and 20' and 21' are carried in axially spaced relationship on sleeve 29. The fingers in each series of fingers are equiangularly spaced about the axis of the sleeve 29 with the alternate fingers in each series projecting upwardly and the intermediate fingers projecting downwardly. Similarly, the upwardly projected fingers or blades in each series of fingers 20 and 21 and 20' and 21 are formed angularly downwardly in one direction relative to the plane of rotation of the fingers while the downwardly projected fingers are provided with a reverse pitch.

Thus, it can be seen that the agitation set up by the rotating fingers 20 and 21, and 20' and 21' serves to prevent the agglomeration of the toner material in the container 1 or to break up any lumps which may form during a period of idleness. During the operation of the dispenser and with the agitation of the toner within the container, the toner is caused to settle on the bottom of the container and the plate 19 for movement of the toner by the plate to the opening 2.

As explained above, during the development of a latent image, the developer material consisting of a mixture of toner and a carrier is applied to the latent image. The toner is attracted to the charged latent image and adheres thereto with most of the carrier particles returning to the developer material container. In order to replenish the toner in the developer material with each operation of the machine, the plunger 4 is operated intermittently to dispense a metered amount of toner into the developer reservoir whereby the proper ratio of toner-to-carrier is maintained.

What is claimed is:

1. A toner dispensing device for use in an electrostatic reproduction apparatus having a developer material reservoir, the combination comprising:

a container for the toner,

an outlet in said container for the passage of toner from the container into said developer material reservoir,

a screen supported within said outlet for sifting the toner,

a plunger supported for reciprocation in said container operable upon actuation in one direction to force toner through said screen,

means for controlling reciprocation of said plunger,

means operable in timed relation to the operation of said controlling means for moving toner to said outlet for dispensing of the toner by said plunger upon operation of said controlling means,

an agitating means for preventing agglomeration of the toner to enable movement of the toner by said moving means, and

a power driven means for driving said controlling means, said moving means and said agitating means.

2. In a device of the character described in claim 1 wherein said controlling means comprises a cam plate rotatable by said power driven means,

a resilient means normally biasing said plunger in said one direction, and

a cam follower carried by said plunger and engaging said cam plate, said cam plate being operable in each revolution to enable operation of said resilient means to actuate said plunger in said one direction subsequent to the operation of said moving means and to return said plunger in the other direction.

3. In a device of the character described in claim 2 wherein said moving means comprises a semicircular disk rotable by said power driven means in a plane intercept ing the path of travel of said plunger, the leading edge of said disk in the direction of rotation being effective to move toner into the path of travel of said plunger in timed relation to the rotation of said cam plate and the operation of said resilient means.

4. In a device of the character described in claim 2 wherein said cam plate is a cylindrical cam having the contoured surface accelerated from 0 to 360.

5. In a device of the character described in claim 3 wherein said power driven means comprises a shaft,

means for driving said shaft, and

a sleeve secured on said shaft for supporting said cam plate and said disk in axial spaced relationship and for carrying said agitating means.

6. In a device of the character described in claim 5 wherein said agitating means comprises a plurality of series of radial blades carried by said sleeve axially spaced intermediate said cam plate and said disk, certain of said blades in each series projecting upwardly and formed angularly in one direction relative to the plane of rotation and the alternate one of said blades projecting downwardly and formed angularly in the opposite direction relative to the plane of rotation.

References Cited UNITED STATES PATENTS 1/1957 Allen 222-235 X 6/1964 Mayo et a1. 222227 US. Cl. X.R. 222235 

